function registerClick(thisform) {
    var username = document.getElementById('username').value;
    var password = document.getElementById('password').value;
    var confirm_password = document.getElementById('confirm_password').value
    if (username != '' && password != '' && confirm_password == password) {
        window.document.register.action = 'index.html';
        alert("就算注册成功也不能登录，因为我不会")
    } else if (password != confirm_password) {
        alert("两次输入的密码不一致！")
    } else {
        alert('账号和密码不能为空！');
    }
}